Effect of Human Hand Dynamics on Haptic Rendering of Stiff Springs using Virtual Mass Feedback

Abstract

Hard surfaces are typically simulated in a haptic interface as stiff springs. Stable interaction with these surfaces using force feedback is challenging due to the discrete nature of the controller. Previous research has shown that adding a virtual damping or virtual mass to the rendered surface helps to increase the stiffness of the surface for stable interaction. In this paper, we analyze the effect of adding virtual mass on the range of stiffness that can be stably rendered. The analysis is performed in the discrete time domain. Specifically, we study the coupled (with human hand dynamics) stability of the haptic interface. Stability, when the human interacts with the robot, is investigated by considering different human hand models. Our analysis shows that, when the human operator is coupled to an uncoupled stable system, an increase in the mass of a human hand decreases maximum renderable stiffness. Moreover, the increase in human hand damping increases the stably renderable stiffness.